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16/03/2009 08:12:35
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P number: P527641
Caption: Feldspar with plates of biotite from the Sletterval No. 3, Upper Quarry, Harris, Outer Hebrides.
Description: The Roneval veins are situated on Sletteval, one of the eastern spurs of Roneval. The topmost or No. 3 quarry lies in the main central part of the vein. The vein has well-defined foot and hanging walls dipping north-north-west at 60 degrees. British Geological Survey Petrology Collection sample number MC 7421. The feldspar makes up c. 75 per cent of the total vein content, with 25 per cent quartz and biotite mica 5 per cent or less. The feldspars average about two to three feet in length but some are up to five feet. In the vein, there are equal amounts of pale pink-coloured spar very regularly rodded and intergrown with quartz, and a darker pink spar more coarsely and irregularly intergrown with quartz.
Date taken: 25/06/1905
Photographer: Unknown
Copyright statement: Unknown
Orientation: Landscape
Size: 243.55 KB; 1000 x 665 pixels; 85 x 56 mm (print at 300 DPI); 265 x 176 mm (screen at 96 DPI);
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Categories: Best of BGS Images/ Rocks and minerals  


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